arXiv subjects

Adam Babinski

Publications and source records attributed to Adam Babinski.

3 recordsLinked to original sources

arXiv2026

Tunable Magneto-Excitonic Coupling in Alloyed van der Waals Antiferromagnet

The unique coupling between magnetic order and photo-generated excitons, electron-hole pairs bound by Coulomb interaction, in layered magnetic semiconductors offers a powerful mechanism for controlling light-matter interactions. In the van der Waals antiferromagnet CrSBr, this coupling is exceptionally strong and manifests distinctly between two coexisting excitonic states: the localised, Frenkel-like XA exciton and the more delocalised, Wannier-Mott-like XB exciton, providing a unique playground for the optical control of magnetism. Here, we reveal how chlorine incorporation reshapes the magneto-optical interplay in CrSBr1-xClx by simultaneously modifying its electronic structure, excitonic properties, and magnetic interactions. Combining magneto-optical spectroscopy up to 85 T with state-of-the-art quasiparticle self-consistent GW (QSGW) calculations on alloy supercells, we show that Cl insertion progressively localises the excitonic wavefunctions and drives both states toward a more Frenkel-like regime. This evolution is accompanied by a systematic reduction of the magnetic-field-induced energy renormalisation, most prominently for the XB exciton. Our work connects exciton character directly to magneto-excitonic coupling. Furthermore, it establishes compositional alloying as an effective strategy for engineering the coupling between magnetic and optical properties in van der Waals magnetic semiconductors.

cond-mat.mtrl-sci↗

arXiv2025

Fast Interlayer Energy Transfer from the Lower Bandgap MoS2 to the Higher Bandgap WS2

Energy transfer (ET) is a dipole-dipole interaction, mediated by the virtual photon. Traditionally, ET happens from the higher (donor) to lower bandgap (acceptor) material. However, in some rare instances, ET can happen from the lower-to-higher bandgap material, depending on the strong overlap between the acceptor photoluminescence (PL) and the donor absorption spectra. In this work, we report an ET process from the lower bandgap MoS2 to the higher bandgap WS2, due to a near 'resonant' overlap between the MoS2 B and WS2 A excitonic levels. Changing the MoS2 bandgap from direct-to-indirect by increasing the layer number results in a reduced ET rate, evidenced by the quenching of the WS2 PL emission. Our work shows at 300 K, the ET timescale of ~33 fs is faster than the reported thermalization of the MoS2 excitonic intervalley scattering (K to K') time and competing with the ultrafast charge transfer timescale. Thus, allowing us to open a new direction in understanding the competing inter/intralayer processes.

cond-mat.mtrl-sci↗

arXiv2017

Raman scattering excitation spectroscopy in monolayer WS$_2$

Resonant Raman scattering is investigated in monolayer WS$_2$ at low temperature with the aid of an unconventional spectroscopy technique, $i.e.$, Raman scattering excitation (RSE). The RSE spectrum is made up by sweeping the excitation energy, when the detection energy is fixed in resonance with excitonic transitions related to neutral and/or charged excitons. We demonstrate that the shape of the RSE spectrum strongly depends on a selected detection energy. The out-going resonance with the neutral exciton leads to an extremely rich RSE spectrum displaying several Raman scattering features not reported so far, while no clear effect on the associated background photoluminescence is observed. Instead, a strong enhancement of the emission due to the negatively charged exciton is apparent when the out-going photons resonate with this exciton. Presented results show that the RSE spectroscopy can be a useful technique to study electron-phonon interactions in thin layers of transition metal dichalcogenides.

cond-mat.mes-hall↗